Electronic circuit breakers may be used in some electrical systems to protect an electrical circuit coupled to an electrical power source from one or more fault conditions. One type of electronic circuit breaker may be a ground fault circuit interrupter (GFCI). GFCIs may be used to prevent electrical shock hazards and are typically used in electrical circuits adjacent to water, such as in bathrooms and/or kitchens. Another type of electronic circuit breaker may be an arc fault circuit interrupter (AFCI). AFCIs may interrupt power to an electrical circuit when an arcing condition within the electrical circuit is detected. GFCIs and AFCIs may also detect other fault conditions such as, e.g., persistent over current and/or short circuit fault conditions. A third type of electronic circuit breaker may be referred to as a dual function circuit breaker, which combines a GFCI and an AFCI. Upon sensing of a fault condition, a trip mechanism within the electronic circuit breaker may be activated to interrupt current flow from the electrical power source to the protected electrical circuit.
An electronic circuit breaker may include an internal power supply that may convert a large AC voltage (e.g., 120 VAC) received from an electrical power source into a low DC voltage. The low DC voltage may be used to power various circuits within the electronic circuit breaker. The various circuits may include integrated circuits (ICs) and/or application specific integrated circuits (ASICs) that perform, e.g., ground fault and/or arc fault detection. However, if a power supply or detection circuit within the electronic circuit breaker fails (because of, e.g., an electrostatic discharge (ESD), a power surge, or a latch-up condition), the fault detection capability of the electronic circuit breaker may be compromised. This may result in a dangerous situation wherein a fault condition may occur in an electrical circuit, but the electrical circuit may remain energized because the electronic circuit breaker may be unable to detect and respond to the fault condition.
To help avoid such a dangerous situation, some known electronic circuit breakers may include a manual test feature, wherein a push-to-test (PTT) button, usually located on the face of the device, can be manually pressed to check that the electronic circuit breaker is operating properly. However, because such manual testing may not be performed, other known electronic circuit breakers may employ an automatic self-test or monitoring feature. Such a feature may automatically check the functionality of the electronic circuit breaker every two or three hours, for example. But if the internal power supply fails, the automatic self-test or monitoring feature may also fail, again resulting in a dangerous situation wherein a fault condition may occur, but the electrical circuit may remain energized.
Accordingly, there is a need for apparatus and methods that monitor and respond to power supply and/or detection circuit failures within an electronic circuit breaker.